An adaptive receiver for receiving a radio frequency (RF) signal and converting the RF signal at an RF frequency FRF toward a low intermediate frequency FIF is disclosed. The adaptive receiver comprises a pair of band pass filters with a nominal center frequency Fc equal to FIF, a look-up table (LUT) configured to estimate a frequency offset Δf, representing the center frequency of the band pass filter due to an operating temperature change and/or process variation, a micro controller configured to estimate the operating center frequency of the band pass filter (=FIF+Δf with the frequency offset included) and use this new center frequency as the adaptive intermediate frequency FIF,AD, and a local oscillator generates oscillating signals at a frequency FLO equal to FRF minus FIF,AD. A temperature sensing device may also be included in this adaptive receiver.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An adaptive receiver for receiving a radio frequency (RF) signal and converting the RF signal at a frequency F RF toward an intermediate frequency (IF) signal at a frequency F IF,AD , the adaptive receiver comprising: a pair of band pass filters, each with a nominal center frequency at F IF , a two-dimensional look-up table configured to provide frequency offset (Δ f ) values of the center frequency of the band pass filters for environmental temperature and process corner variations; a temperature sensing device to provide temperature information; a micro controller configured to, based on the frequency offset (Δ f ) values from the look-up table, the temperature information from the temperature sensing device and pre-stored information on the process corner, estimate an adaptive intermediate frequency F IF,AD equal to the nominal center frequency of the band pass filter, F IF , plus the frequency offset Δ f ; and a local oscillator to generate sinusoidal signals at a frequency F LO equal to F RF minus F IF,AD .
2. The adaptive receiver of claim 1 further comprising two mixers each comprising: a first input to receive the received RF signal; and a second input to receive one of a first and a second local oscillator (LO) signals at the frequency F LO =F RF −F IF,AD =F RF −(F IF +Δ f ), wherein the first LO signal and the second LO signal are orthogonal to one another in phase.
3. The adaptive receiver of claim 2 further comprising a low noise amplifier to amplify the received RF signal.
4. An adaptive receiver for receiving a radio frequency (RF) signal and converting the RF signal at a frequency F RF toward an intermediate frequency (IF) signal at a frequency F IF,AD , the adaptive receiver comprising: a pair of band pass filters, each with a nominal center frequency at F IF , a one-dimensional look-up table configured to provide an intermediate frequency offset Δ f as a function of the difference between two tone voltages, ΔV FX2-FX1 ; wherein the voltage difference ΔV FX2-FX1 (=V FX2 −V FX1 ) is determined based on measured voltages V FX2 and V FX1 for two frequencies; a micro controller configured to, using the ΔV FX2-FX1 value, determine the frequency offset Δ f from the one-dimensional look-up table and compute an adaptive intermediate frequency F IF,AD equal to the sum of the nominal intermediate frequency F IF and Δ f ; and a local oscillator to generate sinusoidal signals at a frequency F LO equal to F RF minus F IF,AD .
5. The adaptive receiver of claim 4 further comprising two mixers each comprising: a first input to receive the received RF signal after amplification by a low noise amplifier; and a second input to receive one of a first and a second local oscillator (LO) signals with the same frequency (F LO =F RF −F IF,AD =F RF −(F IF +Δ f )) and a 90-degree phase difference.
6. An adaptive receiver for receiving a radio frequency (RF) signal and converting the RF signal at a frequency F toward an intermediate frequency (IF) signal at a frequency F IF,AD , the adaptive receiver comprising: a band pass filter with a nominal center frequency at F IF , a one-dimensional look-up table configured to provide an intermediate frequency offset Δ f as a function of the difference of two tone voltages, ΔV FX2-FX1 ; wherein the voltage difference ΔV FX2-FX1 (=V FX2 −V FX1 ) is determined after the adaptive receiver is powered on at temperature T on , based on measured voltages V FX2 and V FX1 for two frequencies; a temperature sensing device to detect the temperature difference Δ T (=T on −T op ) between an operating temperature T op and the temperature T on ; a micro controller configured to, using the ΔV FX2-FX1 value, determine the frequency offset Δ f from the one-dimensional look-up table and compute an adaptive intermediate frequency F IF,AD equal to the sum of the nominal intermediate frequency F IF , Δ f and F slope ×Δ T , where F slope is the F IF +Δ f slope coefficient related to temperature difference Δ T ; and a local oscillator to generate sinusoidal signals at a frequency F LO equal to F RF minus F IF,AD .
7. The adaptive receiver of claim 6 further comprising two mixers each comprising: a first input to receive the received RF signal after amplification by a low noise amplifier; and a second input to receive one of a first and a second local oscillator (LO) signals with the same frequency (F LO =F RF −F IF,AD =F RF −(F IF +Δ f +F slope ×Δ T )) and a 90-degree phase difference.
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October 14, 2009
March 20, 2012
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